0070-climbing-stairs/0070-climbing-stairs.java
class Solution {
    public int climbStairs(int n) {
        int[] dp = new int[n+5];
        dp[0]=0;
        dp[1] =1;
        dp[2] = 2;
        for(int i=3;i<n+1;i++){
            dp[i] = dp[i-1] + dp[i-2];
        }
        return dp[n];
    }
}